What ACR remote knob will work with my original Epicenter or Epicenter Series 2?

The ACR-1 will work with your older model Epicenter®.

It is good to note that it does not have the push/pull function that turned the Epicenter effect on and off like the old remote knob.

If you want to lessen the Epicenter effect with the ACR-1, you just need to turn it all the way down(counter-clockwise).